Field of Invention
This invention relates to a semiconductor process, and particularly relates to a method for fabricating a semiconductor device structure, and to a semiconductor device structure that can be formed with the same method.
Description of Related Art
Some kinds of integrated circuits include high-voltage (HV) MOS devices, such as Input/Output (I/O) devices, for high-voltage operations. Since the operation voltage is high, an HV device requires a thick gate oxide layer.
However, the thick gate oxide layer is so thick that the uniformity of the shallow source/drain (S/D) junction formed by ion implantation through the gate oxide layer is reduced, so that the variation of breakdown voltage of the HV device is large.